Composition and process for cleaning metal surfaces



United States Patent'O 3,247,120 COMPOSITION AND PROCESS FOR CLEANINGMETAL SURFACES James A. Von Pless, Syracuse, N.Y., assignor to CowlesChemical Company, Siraneateles Falls, N.Y., a corporation of Ohio NDrawing. Filed Apr. 30, 1962, Ser. No. 191,251

11 Claims. (Cl. 252114) I Additional objects of the invention are toprovide improvements in the cleaning of the metal surface over presentmethods and compositions.

Many processes for the fabrication of zinc-base die castings involve anoperation in which a coating is applied to the surface of the metal,either for protective or decorative purposes. Thus zinc-base diecastings are electroplated, chromated, painted and otherwise treated toprovide a finished article. In connection with the fabrication, it isessential that the surface of the article to be subjected to theapplication of the coating be free from soils of all kinds which wouldtend to interfere with the uniform adherence of the coating to thesurface of the metal. Buffing compounds used in buffing zinc castingsare particularly difficult to remove. Poorly cleaned castings result ininferior plating. This leads to the blistering which is so common onparts of many modern automo biles. Buffing compounds are compoundedmixtures of abrasive and binder or carrier. The bar type consists ofsolid sticks of high melting fats and waxes plus abrasives. Thesematerials are applied to a bufiing wheel like crayon and melted thereondue to temperature. The liquid type consists of pasty materialscomprising a high melting lubricant and abrasive emulsified in water orkerosene in a high speed mill to suspend materials in the water orsolvent system used. Abrasives used in bufling compounds are, forexample, aluminum oxide, amorphous silica, tripoli, emery and chalk.Examples of binders and carriers are petroleum wax, fat, kerosene,water, vegetable waxes and emulsifiers. Fatty acids (stearic orunsaturated hydrogenated acids), glycerides, beeswax and pitch areexamples of lubricants. W

A method proposed for cleaning metal surfaces to prepare them forsubsequent treatment and particularly coating thereof, involvesimmersing the metal objects in baths containing non-aqueous solvents forgreases; as for example: trichloroethylene and petroleum distillates.Such materials are toxic and require expensive systems for recovery andpurification of the soiled solvents for re-use.

Another method which is more commonly used is an alkaline type bathcontaining fatty acid alkanolamides and amine condensates plus othersurfactants. These materials tend to do a better job of soil removalthan solvents; however, due to the presence of free amines in solutionthey tend to sequester introduced metallic ions and deposit suchsequestered ions (particularly copper) on the surface of the metal to becleaned and therefore having a deleterious effect on subsequentelectroplating processes. These types of baths also are very hard tocontrol operationally and lose their ability to clean with little or noICC warning to the user, thereby shutting down a production lineimmediately. Additions of new chemical to these expired baths are of noavail and will not re-activate the baths to operating levels.

With a view to overcoming these difficulties encountered in productionlines this invention provides maximum wetting of the soils in theminimum of time, high emulsification and dispersion of soils, stabilityof pH at elevated temperatures, anti-corrosion qualities, the ability tocarry large soil loads, and the minimum amount of operational control bytitration methods.

In accordance with the present invention, unusually effective results incleaning, and especially in removing but'ring compounds from zinc diecastings are obtained with the following cleaning composition:

TABLE I Percentage Ingredients: by weight (a) Hydrated borate,calculated as Na B O 10H O (b) Alkali metal soap of highly unsaturatedoil, calculated as cottonseed oil sodium soap having a titer value of29-32 C. 1020 (c) Water soluble lignosulfonate, calculated as sodiumlignosulfonate 1-4 (d) Alkyl ether of polyethylene glycol 2-10 (e)Polyethylene or polymethylene glycol tertiarydodecyl thioether "075-5(f) Alkyl phenoxy polyethoxyethanol 0.75-5 (g) Ethylene glycol monoalkylether 1.5-5 (h) Pine oil 0-0.5

Examples of (a) are borax (Na B O 10H O) and other hydrated borates, forinstance, sodium pentaborate. Borax is preferred because it is readilyavailable and inexpensive. If the pentahydrate is used, the Na O contentis adjusted to meet the decahydrate qualities and an inert material isadded to compensate for the weight differential.

Cottonseed oil sodium soap is preferred for ingredient (b) due to itshigh linoleic acid content. This oil also has a high content of oleicacid but the polyunsaturated acid with two double bonds has a verypowerful detergency for cleaning die castings. Other'soaps of highlyunsaturated fatty acid oils having an iodine value at least as high ascottonseed oil can be used, e.g., sesame oil and safilower oil. I

The water soluble lignosulfonate used as ingredient (c) is preferablysodium lignosulfonate. A preferred sodium lignosulfonate contains notmore than 0.4% by weight calcium oxide, not more than 4.5% by weightreducing sugars, not more than 0.05% by weight iron, about 7.4% totalsulfur and gives a 50% by weight solution in water having a pH value of6.07.5 containing no insoluble materials. This type of substance has adispersing action and also a partial sequestering action for metal ions.

In (d) the alkyl groups can contain one to eighteen carbon atoms (e.g.,methyl, ethyl, 'butyl, decyl, dodecyl, tridecyl, tetradecyl, hexadecyl,octadecyl) and there can be two to twenty oxyethylene groups (e.g.,Tergitol TMN3, TMN6 and TMNIO).

Examples of (e) are Nonic 218, 234, 260 and 261. A preferred material isdecamethylene glycol tertiary dodecyl mono thioether. Other examples ofthioethers in this class are those containing 6 to 18 carbon atoms inthe polymethylene group.

A preferred example of (f) is Makon BXS which contains 12 moles ofethylene oxide. Compounds of this type are made by adding ethylene oxideto an alkyl phenol containing one or more alkyl groups substituted forhydrogen in the phenolic nucleus wherein the alkyl groups contain 9 to18 carbon atoms. Mixtures of such monoand dialkyl phenols which havebeen oxyalkylated with 8 to 30 moles of ethylene oxide per mole ofphenol can be used.

Examples of (g) are the methyl, ethyl, propyl, and butyl ethers ofethylene glycol. These substances act as solvents for the non-ionicsurface active agents (d), (e) and (f). They are also solvent carriersfor small amounts of trichloroethylene, chloroethane, kerosene, Stoddardsolvent, and naphtha that are employed in manufacturing media.

In the following examples, the inhibitive and protective quality of thecleaning composition is supplied by the poly-unsaturated oil soap usedin conjunction-with the specific quantities of mixed non-ionics. If thequantities of mixed non-ionics are removed or altered beyond the limitsset forth the cleaning solution will not function as intended. Operatingconditions of this invention are elevated temperatures of 88-97 C. witha stabilized pH of 8.7-8.9. The protective film provided by thepolyunsaturated oil soap prevents air or water from corroding the basismetal prior to neutralization of the film.

Composite liquid alkaline solutions of the following ingredients wereprepared and tested using proportions of 8-10 oz. of alkaline additiveto one U.S. gallon of water under the aforementioned operatingconditions.

TABLE II Ingredients: Percent by weight Na B O lH O Cottonseed soap(29-32 C. titer) -20 Sod. lingnosulfonate 1-4 Alkylether of polyethyleneglycol such as Tergitol TMN (Union Carbon & Carbide) 2-10 Polyethyleneglycol tertdodecyl thioether such as Nonic 218, 234, 260, 261 (PennsaltChemical Co.) .75-5 Alkyl phenoxy polyethoxy ethanol such as Makon(Stepan Chemical Co.) .75-5 Ethylene glycol mono alkyl ether such asCellosolves (Union Carbon & Carbide) 1.5-5 Pine oil (odor) 0-.5

In general, these additives consist essentially of TABLE IIIIngredients: Percent by Weight Hydrated borate, calculated as Na B O IOHO 68-73 Polyunsaturated oil soap, calculated as cottonseed oil sodiumsoap -10 Other wetting agents 12-17 Table IV gives more specificallyweight percentages of the foregoing additives used in the examples.

Alkaline mixtures as described in Table IV were prepared and dissolvedin the ratio of 8-10 oz. of formula per gallon (U.S.) of water.

Example I Soiled zinc die cast parts were immersed in the cleaningsolution at a temperature ranging from 88-97 C. for a period of from3-20 minutes with rapid emulsification and dispersing action on theremoved soil. No corrosion or darkening of the basis metal wasexhibited.

4- Example 11 Soiled zinc die cast parts were immersed in the cleaningsolution at a temperature ranging from 8897 C. for a period of from 3-20minutes with rapid emulsification and dispersing action on the removedsoil. No corrosion or darkening of the basis metal was exhibited.

Example Ill Soiled zinc die cast parts were immersed in the cleaningsolution at a temperature ranging from 88-97 C. for a period of from3-20 minutes with rapid emulsification and dispersing action on theremoved soil. No corrosion or darkening of the basis metal wasexhibited.

Example 1V Soiled zinc die cast parts were immersed in the cleaningsolution at a temperature ranging from 88-97 C. for a period of from3-20 minutes with rapid emulsification and dispersing action on theremoved soil. No corrosion or darkening of the basis metal wasexhibited.

Example V Soiled zinc die cast parts were immersed in the cleaningsolution at a temperature ranging from 88-97" C. for a period of from3-20 minutes with rapid emulsification and dispersing action on theremoved soil. No corrosion or darkening of the basis metal wasexhibited.

Example VI Soiled zinc die cast parts were immersed in the cleaningsolution at a temperature ranging from 88-97 C. for a period of from3-20 minutes with rapid emulsification and dispersing action on theremoved soil. No corrosion or darkening of the basis metal wasexhibited.

The compositions and procedures of Examples I-VI can also be used in thecleaning of buffed copper and certain aluminum alloys withoutdetrimental effect to the basis metal in the fabrication of such metalsto a finished coated article.

The mixed wetting agents in the examples can be broken down further asshown in the following Table V.

TABLE V Weight percent of total additive Examples I II III IV V VIIngredients:

Sodium lignosulionate 0.5 1. 5 2. 0 2. 0 1. 5 2. 0 'Iergitol TMN 10 5. 53. 5 3.0 4.0 4. 5 5.0 Nonic 260 2. 5 2. 5 2. 5 3. 5 3. 5 3. 5 MakonBXS 1. 5 2.0 2. 5 3.0 3.5 4.5 Butyl Cellosolve. 1.5 3.0 3. 5 2.0 2. 51.5 Pine oil (for odor 0.5 0.5 0.5 0.5 0.5 0.5

Total percent 12. 0 13.0 14. 0 15. 0 16. 0 17.0

Preparations of the ingredients listed in Table IV and performanceslisted under Examples I-VI used in concentrations from 8-10 oz. offormula per US. gallon of water at temperatures ranging from 88-97 C.exhibit excellent soil removal qualities. These compositions givecomplete protection of the basis metal and are unique in the industry,since they contain no amides, amines or phosphates, thereforeeliminating the possibilities of copper deposition by immersion. Thecompositions of the invention are stable during operation, havetremendous soil capacity and have a stable pH.

The introduction of plating solution (specifically CrO in small amountsto the cleaning solution does not hinder its ability to clean, nor willit deposit metallic ions on the basis metal by immersion means (e.g.,copper by immersion plate).

The invention also is unique in that the basis metal can be immersed forextended periods of time (up to 20 min.) without showing signs ofcorrosion or ionic metal deposition.

The invention is hereby claimed as follows.

I claim:

1. A composition adapted to be added to Water to produce a cleaningcomposition and consisting essentially of the following ingredients inweight percent based on the total Weight of the composition beforeaddition to water:

Ingredients: Percentage by Weight (21) Hydrated sodium borate,calculated as the Na B O 1011 equivalent weight 68-73 b) Alkali metalsoap of highly unsaturated fatty oil having a titer value of 29-32" C.(c) Water soluble sodium lignosulfonate (d) Alkyl ether of polyethyleneglycol contain 1 to 18 carbon atoms in the alkyl groups and 2 to 20oxyethylene groups (e) Polyalkylene glycol tertiarydodecylthioether fromthe group consisting of polyethylene glycol tertiarydodecylthioethersand polymethylene glycol tertiarydodecylthioethers containing 6 to 18carbon atoms in the polyalkylene group 0.75- (f) Alkyl phenoxypolyethoxyethanol containing 9 to 18 carbon atoms in the alkyl groupsand 8 to 30 moles of ethylene oxide per mole of phenol 0.75-5 (g)Ethylene glycol monoalkylether containing 1 to 4 carbon atoms in thealkyl group (b) Pine o-il 2. A liquid cleaning composition consistingessentially of the composition of claim 1 dissolved in water in theproportions of 8 to 10 ounces of the composition of claim 1 per gallonof water.

3. A composition as claimed in claim 1 in which (b) is cottonseed oilsodium soap.

4. A composition as claimed in claim 1 in which (e) is decarnethyleneglycol tertiary dodecylmonothioether.

5. A composition as claimed in claim 1 in which (f) contains 12 moles ofethylene oxide.

6. A process of cleaning metals which comprises washing them with acomposition as claimed in claim 1 dissolved in Water in proportions from8 to 10 ounces of said composition per gallon of water at a temperatureof 88 C. to 97 C. at a pH of 8.7 to 8.9.

7. A process as claimed in claim 6 in which the metal surface to becleaned is a zinc base die casting.

8. A process as claimed in claim 6 in which the metal surface to becleaned is a buffed copper surface.

9. A process as claimed in claim 6 in which the metal surface to becleaned is an aluminum alloy surface.

10. An additive adapted to produce a liquid cleaning composition whenadded to water consisting essentially of the following ingredients inWeight percent based on the total Weight of the composition:

Ingredients: Percentage by weight NEIZBQOTIOHZO Cottonseed oil sodiumsoap having a titer value of 29-32 C Other ingredients from the classconsisting of sodium lignosulfonate, alkyl ethers of polyethyleneglycols containing 1 to 18 carbon atoms in the alkyl groups and 2 to 20oxyethylene groups, polymethylene glycol containing 6 to 18 carbon atomsin the polymethylene group, alkyl phenoxy polyethoxyethanols containing9 to 18 carbon atoms in the alkyl groups and 8 to 30 moles of ethyleneoxide per mole of phenol, ethylene glycol Inonoalkyl ethers containing 1to 4 carbon atoms in the alkyl groups, and pine oil 11. A compositionadapted to be added to water to produce a cleaning composition andconsisting essentially of the following ingredients:

Ingredients: Percent by weight (a) Sodium tetraborate decahydrate 67-73(b) Sodium soap of cottonseed oil (29-32 C. titer) 10-20 (0) Sodiumlignosulfonate 1-4 (d) An alkylether of a polyethylene glycol containing1-18 carbon atoms in the alkyl groups and 2-20 oxyethylene groups 2 2-10(e) Polymethylene glycol tertiarydodecylmonothioether containing 6-18carbon atoms in the polymethylene groups 0.75-5

(f) Alkylphenoxy polyethoxyphenol containing 9-18 carbon atoms in thealkyl groups and 8-30 moles of ethylene oxide per mole of phenol a-0.75-5

(g) Ethylene glycol monalkylether containing 1-4 carbon atoms in thealkyl group 1.5-5 (h) Pine oil 0-0.5

References Cited by the Examiner UNITED STATES PATENTS 2,097,737 11/1937Pickett et al. 252-121 XR 2,595,300 5/1952 Safrin et al 252-1092,664,399 12/1953 Kluender 252-109 XR 2,954,348 9/1960 'Schwoeppe252-121 XR 3,048,547 8/1962 Vosbogian 252-154 XR FOREIGN PATENTS 671,3585/1952 Great Britain.

OTHER REFERENCES Bennett: The Chemical Formulary, (vol. V), Chem. Publ.Co., Brooklyn, NY. (1941) (p. 572).

JULIUS GREENWALD, Primary Examiner.

1. A COMPOSITION ADAPTED TO BE ADDED TO WATER TO PRODUCE A CLEANINGCOMPOSITION AND CONSISTING ESSENTIALLY OF THE FOLOWING INGREDIENTS INWEIGHT PERCENT BASED ON THE TOTAL WEIGHT OF THE COMPOSITION BEFOREADDITION TO WATER: INGREDIENTS: PERCENTAGE BY WEIGHT (A) HYDRATED SODIUMBORATE, CALCULATED AS THE NA2B4O7$10H2O EQUIVALENT WEIGHT 68-73 (B)ALKALI METAL SOAP OF HIGHLY UNSATURATED FATTY OIL HAVING A TITER VALUEOF 29-32*C. 10-20 (C) WATER SOLUBLE SODIUM LIGNOSULFONATE 1-4 (D) ALKYLETHER OF POLYETHYLENE GLYCOL CONTAIN 1 TO 18 CARBON ATOMS IN THE ALKYLGROUPS AND 2 TO 20 OXYETHYLENE GROUPS 2-10 (E) POLYALKYLENE GLYCOLTERTIARYDODECYLTHIOETHER FROM THE GROUP CONSISTING OF POLYETHYLENEGLYCOL TERTIARYDODECYLTHIOETHERS AND POLYMETHYLENE GLYCOLTERTIARYDODECYLTHIOETHERS CONTAINING 6 TO 18 CARBON ATOMS IN THEPOLYALKYLENE GROUP 0.75-5 (F) ALKYL PHENOXY POLYETHOXYETHANOL CONTAINING9 TO 18 CARBON ATOMS IN THE ALKYL GROUPS AND 8 TO 30 MOLES OF ETHYLENEOXIDE PER MOLE OF PHENOL 0.75-5 (G) ETHYLENE GLYCOL MONOALKYLETHERCONTAINING 1 TO 4 CARBON ATOMS IN THE ALKYL GROUP 1.5-5 (H) PINE OIL0-0.5